In the lumber industry, boards are typically created through multiple sawing steps. A relative cylindrical or conical log will first be sawed length-wise to create unfinished planks or “flitches” which have a uniform thickness, but whose opposing edges (“wanes”) are still uncut and therefore non-uniform. To create a board with constant width (i.e., uniform edges), a second sawing step is performed which cuts away a predetermined amount of the wanes. In order to optimize the amount of lumber obtained from each unfinished flitch, the flitch should enter the second sawing step at a certain orientation, typically in terms of the relationship between the centerlines of the flitch and the sawing apparatus.
Typically the unfinished flitches are fed along a conveyance system to a saw station to accomplish this second sawing step. The conveyance system may comprise a belt, chain, or a series of rollers on which the flitch rests and which moves the flitch toward the sawing station. The conveyance system may also include a series of side rollers to prevent the flitch from moving laterally as it engages the saw blades in the saw station. In some instances, the side rollers may be independently adjustable to impart specific orientations on the flitch.
Techniques are also known in which the wanes of a flitch are sensed or measured by an optical or mechanical measuring system. These measurement results are fed to a computer system programmed to calculate the orientation of the flitch relative to the saws which will provide the optimal cutting solution. These systems can then produce control signals which will automatically position the side rollers or other alignment devices such that the flitch assumes the optimal cutting orientation. Despite advances in sawing techniques such as described above, there still exists the need for improve methods and apparatuses for accurately and reliably positioning flitches (or any other items or work pieces) as those items travel along a conveyance system.